An immunoassay method is known which corrects the amount (assay value) of antibody or antigen in blood obtained by immunoassay of a whole blood specimen based on a hematocrit value obtained from a blood analyzer, so as to obtain the amount of antibody or antigen (corrected value) in the serum or plasma (refer to Japanese Laid-Open Patent Publication No. 10-48214).
In this method, when the specimen has an abnormally low hematocrit value, a problem arises inasmuch as an accurate correction value (amount of antibody or antigen in the serum or plasma of the specimen) cannot be obtained.